USB (Universal Serial Bus) is a well-known communication standard, which has been upgraded from a known USB 2.0 standard to a current USB 3.0 standard, also known as high speed USB, wherein the transmission speed of USB has been increased from 480 Mbit/s to 5 Gbit/s. However, USB 3.0 standard has very rigorous requests on the structure design and the electrical performance of the electrical connector interface for transmitting high speed signals.
FIG. 1A is a perspective view of two rows of terminals of a known USB connector, including a row of low speed circuit terminals 210 for transmitting low speed signals and a row of high speed circuit terminals 220 for transmitting high speed signals. The row of high speed circuit terminals 220 are positioned above the row of low speed circuit terminals 210.
FIG. 1B is an exploded view of the two rows of terminals of FIG. 1A. The row of low speed circuit terminals 210 includes a power terminal Bus, a ground terminal G1, and a pair of low speed differential signal terminals S0, S0′. The row of high speed circuit terminals 220 include a ground terminal G2 and two pairs of high speed differential signal terminals S1, S1′, S2, S2′.
Referring to FIGS. 1A and 1B, the ground terminal G2 of the row of high speed circuit terminals has a same width as any one of the high speed differential signal terminals S1, S1′, S2, S2′, therefore, there is a relative large mutual inductance generated in the high speed circuit, causing inductive coupling crosstalk between the two pairs of high speed differential signal terminals S1, S1′, S2, S2′. A connection portion 221 of each terminal of the row of high speed circuit terminals 220 extends in straight line in its whole length, and a connection portion 211 of each terminal of the row of low speed circuit terminals 210 also extends in straight line in its whole length. Accordingly, the connection portions 221 of the high speed circuit terminals 220 are parallel to and spaced from the connection portions 211 of the low speed circuit terminals 210 by a constant space.
However, in the known connector, as shown in FIG. 1A, the high speed circuit terminals 220 are spaced from the low speed circuit terminals 210 by a relative small space, causing capacitive coupling crosstalk between the high speed circuit terminals 220 and the low speed circuit terminals 210.
FIG. 3 is a perspective view of a shield 30 for a known high speed USB connector, which is not provided any additional ground terminal on the shield 30. Therefore, it may further increase the mutual inductance generated in the high speed circuit, and further increase the inductive coupling crosstalk between the two pairs of high speed differential signal terminals S1, S1′, S2, S2′.
FIG. 2A shows a plastic insulation body of a known high speed USB connector. FIG. 2B is an exploded view of the plastic insulation body shown in FIG. 2A. The plastic insulation body of the known USB connector includes a base 10 and a rear retaining portion 60 separate from the base 10. After being assembled in the insulation body, as shown in FIG. 2B, each terminal is almost enclosed in the plastic insulation body only excluding a contact portion and a pin portion. Thereby, each of high speed differential signal terminals has a relative high dielectric constant, causing a signal transfer delay of the high speed differential signal terminal during transmitting signals.
Considering above disadvantages of the known high speed USB connector, such as the crosstalk between the high speed differential signal terminals and between the high speed differential signal terminals and the low speed differential signal terminals, and the signal transfer delay of the high speed differential signal terminals, it has been demanded to develop a new or novel high speed USB connector capable of overcoming or alleviating at least one aspect of the above mentioned disadvantages.